Recovery of sterols



Nov. 6, 1951 R. M. cHRlsTENsoN RECOVERY OF' STEROLS Filed May 9, 1950 Patented Nov. 6, 195,1

RECOVERY F STEROLS Roger M. Christensen, Milwaukee, Wis., assignor to Pittsburgh Plate Glass Company, a corporation of Pennsylvania Application May 9, 1950, Serial No. 160,919

11 claims. (ci. 26o-397.2)

The present invention relates to methods of obtaining concentrates of sterols and it has particular relation to methods of obtaining concentrates of sterols from higher fatty acids from soap stocks such as result from the refining of glyceride oils.

One object of the invention is to concentrate the sterols in a crude source of sterols, 'such as a soap stock, into a small fraction from which they can be more readily recovered than from the original material.

A second object of the invention is to provide a method lof concentrating unsaponifiable matter of a mixture of fatty acids with concomitant separation of the higher fatty acids into a fraction of high iodine value land a fraction of low iodine value.

A third object of the invention is to provide a method of obtaining a concentrate of sterols from a pot residue from the distillation of fatty acids from a crude material such as a soap stock.

A fourth object of the invention is to provide a method of fractionating the higher fatty acids derived from a soap stock whereby to separate the crystallizable sterols from the liquid unsaponiiiable matter.

These and other objects of the invention will be apparent from consideration of the following specification and the appended claims.

It has heretofore been recognized that most glyceride oils, in addition to glycerides of higher fatty acids, free fatty acids and break, include certain amounts of unsaponiable materials such as sterols and other constituents. The sterols when pure are crystallizable. solid materials. They are of great value in the pharmaceutical field and for other applications. A large number of 'methods of recovering these sterols from glyceride oils, such as soybean oil, have been proposed. However, most of these methods have been tedious and expensive, have resulted in inferior products or have resulted in degradation of the raw materials, so that the price of concentrated or purified sterols has remained high in spite of the fact that they constitute almost universal components of glyceride oils of both animal and vegetable origin. f i

The present invention contemplates the provision of a process for the recovery of Vsterols of glyceride oils which can be applied to a crude, inexpensive source of sterols, which is relatively 2 simple, inexpensive and results in a sterol concentrate of high quality; all of these advantages being attained concomitantly with the isolation `of fatty acid fractions of high technical value.

The present invention involves the provision of a process in which sterols are successfully concentrated in a raffinate fraction from the 'extraction of free fatty mixtures such as so-called foots acids with a polar solvent.

The principles of the present invention are applicable to various mixtures that include free fatty acids and sterols. However, it is especially well adapted to application to so-called soap stocks which include soaps of the free fatty acids of glyceride oils and unsaponifiable matter in a substantially increased concentration as compared with the original oil. 'I'hese soap stocks are usually produced in the alkali refining of glyceride oils such as soybean oil, cottonseed oil, linseed oil, peanut oil. corn oil, sunflower seed oil, cocoanut oil and the like. In the refining operation, the oils may be treated with small percentages, e. g. 0.1 to 2 or 3% by weight of an alkaline substance such as sodium hydroxide or sodium carbonate, thus neutralizing free fatty acids in the oil to form soaps and also eliminating break and gums in the oil. Alkali refining is discussed in the text Industrial Oil and Fat Products, Alton E. Bailey, copyrighted 1945 by Interscience Publishing Company, New York, N. Y., pages 502-517. There remains in the oil, after alkali treatment, a sort of sludge including the soaps which can be removed by settling or centrifugation. The material centrifuged o comprises soaps of free fatty acids, unsaponifiable matter such as sterols, and a certainamount of valuable glyceride oil and probably other constituents. The product is conventionally termed foots and is of materially reduced value as compared with the original oil or the refined oil.

The foots," as above indicated, are greatly enriched in sterols as compared with the original oil and it is a main feature of the present invention that these sterols are recovered in a highly valuable form. It is also a feature of the invention that the fatty acids which are present in the foots as glycerides or as soaps are fractionated upon the basis of degree of unsaturation and usually can be recovered in a purified form of high technical merit.

In applicants process, a first step is to proawassi 3 vide a sterol-containing mixture of fatty acids in which the acid components are largely in the free or uncombined state. Assuming that the raw' materials are roots from alkali refining of a fat or oil such as soybean oil, the conversion may conveniently be effected by treating the mixture first with excess alkali to saponify any glycerides present in the foots then with a strong acid such as sulfuric acid to liberate the free fatty acids. The alkali salts of the mineral acids can be washed out with water. It is to be understood that liberation of the fatty acids from glycerides of an oil can also be effected by other techniques, such as Twitchellization, or by catalytic hydrolysis or by high pressure splitting.

The precise mode of splitting glycerides does not constitute a feature of the invention.

A mixture of free fatty acids containing sterols. in accordance with the provisions of the present invention, may be fractionated with concentration of sterols in the raffinate, by application of a polar solvent which is but partially miscible with glyceride oils.

A considerable number of polar solvents is disclosed in Patent 2,278,309 to Stephen E. Freeman. Polar solvents especially suitable for the purpose include furfural and methyl acetoacetate which function smoothly and well with naphtha as a non-polar solvent. Furfural, if employed, may be dry, or preferably it is partiallv or completely saturated with water.

In most instances, it is also desirable to include in the system a non-polar solvent of lipoid matter, such as naphtha, e. g. petroleum naphtha of an average chain length of 6 to 10 carbon atoms per molecule and which is immiscible with, or but partially miscible with the polar solvent. Such non-polar solvents, within certain ranges of temperature function to develop the selectivity of the polar solvent for unsaturated acids and other non-sterols.

The mixture of fatty acids and sterols may be merely dissolved in one component of the solvent system, e. g. the naphtha, and then agitated with or otherwise contacted with a polar solvent in a conventional batch extraction. Of course,

sumciently spaced from the extremities of -the lcolumn to provide zones of clarification or it is also contemplated to contact the sterol-containing mixture with non-polar solvent and polar solvent without preliminary solution in either component. In a batch operation, the solvent system, when thoroughly contacted with the sterol-containing material,` may be allowed to stand quiescent for a short period of time. 'Ihe non-polar solvent will separate into one layer which is herein designated as the raiiinate phase and the polar solvent will separate into another layer which is designated as the extract phase. If appropriate conditions of operation are maintained, more highly unsaturated free fatty acids, together with certain unsaponifiable substances of oily nature. will be dissolved out in the extract or polar phase, while the more saturated fatty acids and the sterols will be retained in the railinate or non-polar solvent phase.

While the invention is susceptible of batch operation, it is usually preferred, for various reasons, to conduct it in a continuous, countercurrent manner. This can readily be effected by introducing a sterol-containing mixture of fatty acids into an intermediate portion of a vertically elongated column and simultaneously introducing naphtha or its equivalent non-polar solvent near one extremity of the column and the polar solvent near the other extremity. The points of introduction of the solvent media should be settling from'which the phases can be drawn off for further treatment. if

Itis also contemplated to effect countercurrent contactv of the mixture of sterols and fatty acids with the solvent media in centrifuges of the so-called Podbelniak type in which the solvent media and the liquid to be extracted are causedy to flow in opposite directions by centrifugal force about theconvolutions of a perforated diaphragm involutely coiled about the axis of centrifugation. In such centrifugal extraction, the heavier liquids are drawn off at the outer periphery of the system and the lighter liquids, of course, are drawn off at the axis. Appropriate systems of this type are disclosed in U. S. Patents 2,286,157, 2,209,577, 2,281,796, 2,109,375, 1,936,523 and likewise the application of a co-worker, Stewart W. Gloyer, Serial No. 51,026, filed September 24, 1948.

Assuming a system involving use of an elongated column for contacting the fatty acid material and the mutually immiscible or partially miscible solvents. the mixture of unsaponiilable matter and fatty acids wil be introduced near the mid portion of the column, the furfural will be introduced at a point spaced somewhat below the top ofthe column to provide an upper clearing zone, and the naphtha will be introduced at a point somewhat about the bottom of the column to provide a lower clearing zone. The extract phase comprising furfural'in which is dis solved a concentration of more unsaturated fatty acids and non-sterol unsaponiable matter, usually of an oily nature, and also some dissolved naphtha will be drawn oi at the bottom of the column. The raffinate will comprise a concentration of more saturated fatty acids, unsaponiable matter including sterols. It will also contain most of the naphtha and will be partially or completely saturated with furfural.

The present invention is especially concerned with the treatment of the rainate phase containing, as above stated, sterols and other unsaponiable constituents. It may be that, for some purposes, this fraction can be used without other treatment than the distillation of the solvents. This can be effected by vacuum or by steam distillation. In most instances it is preferred, however, to further purify the raflinate fraction containing the major portion of the sterols of the original fatty acid-unsaponiable matter mixture.

A number of different techniques of eliminating or reducing the proportion of the fatty acids with respect to the sterols in the rainate fraction are possible. One convenient method comprises subjecting the raflinate, after the solvents have been removed therefrom, to a distillation operation. Preferably such distillation should be conducted under fairly low pressures, e. g. 1 or 2 millimeters of mercury or even lower. The temperature should also be fairly low, namely Within a range of 200 to 300 C. or at such temperature as will obviate undue decomposition of the sterols in the course of the distillation. Temperatures within the range of 225 to 275 C. at pressures of 1 millimeter of mercury are found to produce very satisfactory results on raiiinates from cottonseed, soybean, linseed and similar oil foots.

The residue comprising fatty acids and sterols resulting from the distillation of the rainate product as Aabove described can be used directly as a source rich in sterols in various applications.

owever, if it is desired further to refine the sterols, a number of different techniques are available. For example, it would be readily possible to re-extract the distillation residue with the system of polar solvent and non-polar solvent as already described in order to remove additional amounts of fatty acids and to concentrate the f sterols.

4 metal released may be introduced into the conalcohol such as methyl alcohol, ethyl alcohol or v isopropyl alcohol. The resultant compositions may comprise water within a range of to 62% by weight, an alcohol within a range of 12 to 65% by weight, and saponified distillation residues 5 to by weight. The mixtures may then be countercurrently contacted with naphtha in an appropriate column, the solution being introduced at the top and the naphtha at the bottom. This i technique is Well adapted for treating rafnates high in unsaponiiiable matter. These may be obtained by taking off a raffinate of low yield.

The concentrates of sterols relatively free of fatty acids may then be subjected to anv of the well known procedures for purifying sterols. For example, they may be crystallized from solvents such as acetone and the like.

An appropriate embodiment of apparatus for effecting the fractionation of mixtures of fatty acids and sterols and other unsaponiable matter, in accordance with the provisions of the present invention, is illustrated in the drawing in which the single figure constitutes a diagrammatical flow sheet.

The apparatus illustrates the use of a soap stock, such as that resulting from the refining of soybean oil or similar oil, as the crude sterolcontaining material. It is assumed that this material is further treated With alkali to saponify any residual glycerides in the stock and that the soaps are acidifled and the mixture is washed to eliminate salts of the acid employed in the acidification. Any other source of fatty acids reasonably rich in sterols might be employed under the provisions of the invention.

In the apparatus shown, a container i0 is provided for soap stocks containing sterols and perhaps other unsaponiable matter as well as soaps of fatty acids and usually a certain amount of oily unsaponiable matter which is nonsterol in l character. Glycerides of fatty acids may also be entrained. A line Il conducts this soap stock to a saponifier l2 which may be heated by any appropriate means such as an electrical resistance coil I3. In the container, the soaps are admixed with additional alkali, such as sodium hydroxide introduced through a line I4. 'Ihe amount of alkali is based upon the glyceride content of the soap stock which can easily be determined by routine analysis. The stocks are heated in the container until all, or nearly all, of the glycerides are converted into soaps. Subsequently the mixture of soaps, unsaponiable matter and glycerine is discharged through a line I6 to an acidiiier I1 which may be provided with all necessary heating elements such as electrical resistance coils I8 or other suitable heating devices. The acidier may also be provided with a mechanical agitator (not shown) to agitate the contents. Acid such as sulfuric acid or other acids tainer l1 through a line vI 9. In the container the mixture, including the sterols to be recovered, is permitted to remain at reaction temperature until practically all of the soaps are broken down to release free fatty acids.

The acidied mixture may be discharged from container I1 through a line 2l to a lower portion of a washer 22 into which water can be introduced through a line 23. Washing can be maintained by me ans of water until substantially all of the alkali metal salts and glycerine contained in the mixture of'free fatty acids and unsaponlable matter has been removed.

The mixture of water, alkali metal salts and glycerine are discharged from the washer 22 through a line 26 which may lead to apparatus i not shown) for recovery of the values contained therein. Valves V are provided in the Several lines Il, I4, |6,-I9, 2| and 26 to permit control of the flow of liquids in the lines.

The mixtureof free fatty acids and unsaponifiable matter from the washer discharges through a line 21 to a receiver 28 that acts as a storage or surge tank from which the mixture can be drawn at a uniform rate through a line 29 and fed to a fractionating zone or column 3l. The

line 29 is indicated as being provided with a pump 32 by means of which the flow of material to the column may be maintained at any rate desired. Obviously pumps may be placed in the system at any point where flow cannot be maintained naturally owing to the effects of gravity or to any other effects likely to be encountered. Preferably,r line 29 will be connected to the column 3l at a point near the mid zone thereof, for example at a point Within one quarter of the total length of the extraction zone from the middle of said zone. An appropriate zone for the int-roduction of the feed of free fatty acids and unsaponiable matter is indicated in brackets at Z. The column should be provided with baffles. bubble plates, packings of Berl saddles, Raschig rings or other means to promote uniform, nonchanneled distribution of the countercurrently flowing liquids in the column.

Appropriate sight holes 3|a may be provided at intervals in the column for observingrthe conditions in the column. In this manner, the position of the interface between the extract and the raffinate phases can be observed. Branch lines 35a and 48a may also be provided in outlets 35 and 6B and through which samples of extract or raffinate solutions can be drawn off for settling and observation, to determine if phase separation in the column is complete. Adjustments of the rate of feed or temperature of operation can then be made to maintain good phase separation.

A polar solvent such as furfural or ethyl or methyl acetoacetate or the like may be fed through a line 33 to an upper portion of the column in such manner as to provide an upper clearing zone C. Non-polar solvent, such as petroleum naphtha, is introduced into the column through a line 34 at a point sufllciently above the bottom thereof to provide a lower clearing zone C-i.

An extract solution of polar solvent containing selectively dissolved therein the more unsaturated acids of the feed stock along certain oily, unsaponifiable matter is drawn. on? at the bottom of the clearing zone C-I through a line Steam and solvents pass oi as vapors through' line l1 to a solvent recovery apparatus (not shown). The mixture of oily, unsaponiiiable matter and more unsaturated fatty acids discharges from the still through line 38 to a temporary storage or surge tank 39 designed continuously to receive the extract product from column 3 l The mixture of free fatty acids and unsaponifiable matter of oily nature from the steam stripping operation may be stored in a container until an adequate charge thereof is collected. This is then fed to a still 4| which may be heated by convenient means such as coils of electrical resistanceelements 42. Under these conditions, the more unsaturated free fatty acids are to a large extent distilled and pass off through the head 43 of the still and are discharged to a storage container 44.

Pot residue comprising oily unsaponiiiable matter and a considerable amount of polymerized fatty acids passes off from the still through a line 46 and may be stored or subjected to further treatment. The container 44 is indicated as being connected by the line 41 to a source of vacuum (.not shown) whereby the still 43 may be maintained at any desired pressure.

-Raiiinate from column 3l, comprising more highly saturated fatty acids and sterols dissolved in naphtha, pass olf from the upper clearing zone C through a line 48 to evaporator 49 for partial removal of solvent, then it passes to a stripping still 49a in which the naphtha and any residual furfural are stripped, for example by steam distillation. To this end, steam is introduced at 49h. Solvent vapors and steam pass off through line 50 to solvent recovery apparatus (not shown).

The mixture of free fatty acids and unsaponiable matter comprising primarily the sterols in greatly concentrated form pass off from the still through a line i to a temporary storage container 52 which acts as a surge tank and from which the mixture can be drawn intermittently through a line 53 to charge a still 54. This still may be heated by convenient means, such as resistance coils 56, and vapors of free fatty acids therefrom pass upwardly to head apparatus 51 and are discharged to storage in a container 58. A vacuum may be maintained upon the still apparatus by means of a line 59 from the container l5 connected to a sourcel of vacuum (not shown). Usually the pressure in the still will be of the order of 1 or 2 millimeters of mercury (absolute). It may be as low (in absolute terms) as conveniently can be maintained. The maintenance of high vacuum (or low pressure) is desirable since it promotes the distillation of free fatty acids from the raiiinate product with minimum decomposition or deterioration of the sterol content. The free fatty acids collected in the container 58 are of good color, of relatively low degree of unsaturation and excellently adapted for many technical applications.

A still residue comprising some free fatty acids and a high concentration of sterols passes on from the still 54 at the bottom thereof through a line BI and may be transmitted to apparatus 'suitable for further processing of the mixture along conventional lines heretofore employed in the purication of sterols, e. g. saponication and extraction followed by crystallization from appropriate solvents. It is also contemplated that the still residue may be transmitted to storage without any special attempt further to purify the sterol content.

Crude material suitablefor use in the practice of the invention preferably comprises an acidied soap stock or a soap stock that can be acidifled in which the sterols of a glyceride oil have been substantially concentrated. These soap stocks, as already indicated, are usually obtained in the alkali refining of glyceride oils. They may be from various sources including linseed oil, soybean oil, cottonseed oil, peanut oil,

' forming distinct phases.

corn oil and others. In some instances, it may also be desirable to treat crude mixtures of fatty acids, and unsaponiflable matter derived from tall oil in accordance with the provisions of the invention to concentrate unsaponiable matter.

Usually the crude stocks contain glycerides entrained with the soaps and unsaponiflable matter. Prior to solvent fractionation of the stocks, such glycerides may be appropriately broken to liberate fatty acids. This may conveniently be accomplished by heating the stocks with additional alkali to transform the glycerides into soaps and glycerine. Subsequently, the mixture may be acidied with sulfuric acid or other strong acid to liberate the free fatty acids from the soaps. The acidified mixture may also be heated with dilute sulfuric acid for purposes of reducing emulsication in subsequent extraction operations. Treatment of the material with agents to break up emulsifications is not precluded.

A number of diierent crude materials were examined or analyzed for unsaponiflablematter and the results are tabulated as follows:

The polar solvents by reason of polar groups contained therein display a preference for fatty acids which also are relatively polar while the non-polar solvents tend selectively to dissolve the unsaponiflable matter including sterols which are of relatively slight polarity. Obviously the polar solvent should be but partially miscible with the non-polar solvent or the soluton of polar solvent and fatty acids constituting the extract. In other words, the several components of the system in the extraction zone must be capable of There must also be a difference of density between the liquid phases to promote mutual flow 'through each other. Furfural, for example, is of relatively high density and naphtha is of relatively low density. Glyceride oil is also of relatively low density.

The furfural phase then tends to fall and the.

naphtha phase tends to rise through it to provide distinct strata or layers.

These mixtures of fatty acids and unsaponifiable matter may be fed continuously into a system such as column 3l through line 29, illustrated in the drawing, and intimately contacted with various polar solvents designed to take. up a liquid extract and non-polar solvents designed to take out a liquid railinate` phase in which the sterols are substantially concentrated. Solvents such as those disclosed in Freeman Patent 2,278,309 are contemplated as polar media Furfural is probably one of the best of the polar solvents and, in most instances, furfural which has been saturated or partially (10 to 90% by weight) saturated with water at the temperature of operation is preferred. Small amounts of water, e. g. or 10% or less, may also be includedwith various other solvent media provided thevsolubility of the fatty acid mixture in the solvent is not too low. The polar solvent. such as furfural, may be employed in a proportion of 2 to 30 parts by volume per part of fatty acids.

The non-polar solvent for feeding into the column at the end opposite that of introduction of the polar solvent or in admixture with the feed of fatty acids and unsaponifiable matter may be selected from various liquid media which are insoluble, or are but incompletely soluble in the polar solvent-oil mixture Naphtha, such as paraflinic naphtha, containing an average of 6 to 10 carbon atoms per molecule is very satisfactory as a non-polar medium. In the practice of the invention, the feed of non-polar solvent preferably will be within a range of .2 to l0 parts per part of feed of fatty acids and unsaponifiable matter. As previously indicated, the non-polar solvent may be introduced below the feed of stock, or, if desired, it may be mixed at least in part with the latter. It is also contemplatedv to introduce a part of the non-polar solvents in solution with the feed and to introduce the remainder at a point below the introduction of the feed. Such system is very desirable if the fatty acid stock ,is of high melting point and tends to be solid at the temperatures of operation. It is desirable that all components of the system in the column 3| be in liquid phase;

The temperature of operation of the column 3|, of course, for optimum results will vary somewhat for different sources of crude material and also for different solvents. In general, a temperature within a range of 60 to 200 F. is deemed to be within the provisions of the invention but could be much higher if desired.

' SUMMARY OF OPERATING CONDITIONS Crude fatty acids.. 1 part Naphtha, .2 to 10 Furfural 2 to 30 Temperature 60 to 200 F.

.Solvent feed rate: So adjusted that a phase interface will form in the column and raffinate oil phase will not be carried out of the column along with the extract solution and extract solution will not be carried out by the raffinate.

The following examples illustrate the application of the principles of the invention to the sepaparation of concentrates of sterols from particular crude materials:

Example I 10 all, of the fatty glycerides contained therein. The saponied mixture was then brought to a pH value of 2 by the addition of 225 pounds of sulfuric acid of 98% concentration. A commercial de-emulsifying agent was added and the mixture was stirred at 200 F. for 12 hours.

\The mixture was allowed to settle until it separated into an upper layer of fatty acids of black color which was drawn 01T. Approximately 800 pounds of fatty acidswere separated.

The fatty acid mixture was stirred at 180 to F. for 20 hours with 300 pounds of 15% shulfuric acid in order to eliminate any emulsifying agents which might be present in the oil. The

mixture was then washed with water until watersoluble acids, salts, glycerol and the like were removed, thus leaving a mixture consisting essentially of free fatty acids and unsaponifiable matter. Possibly small amounts of fatty acid glycerides also remalned. The fatty acid mixture was of the following characteristics:

Iodine value 149.9

Acid value 180.0 Unsaponiable matter 3.96 Color Black Percent by weight distillable acids 78.5

Three separate runs were conducted in the column 3l with the acid mixture so obtained. The column was of 3 inch diameter though, of course, for higher production, columns of larger diameter could be employed. The fatty acid feed, in a proportion of 1 part by volume, was introduced through the line 29 in solvent-free state but could have been diluted with naphtha, if so desired. The feed line 29 for fatty acids entered the column at approximately 28 ft. above the inlet of line 34 for naphtha and 47.5 ft. below the inlet 33 for polar solvent, namely furfural. Furfural saturated with water was employed in a ratio of 8 volumes per volume of feed. Naphtha was added in a ratio of from 6 to 2.67 parts by volume per part of feed. The feeds were so adjusted that phase separation could take place and the raffinate phase cleared at the top of the column was practically free of polar solvent exexcept such as was actually dissolved while the extract phase at the bottom of the column was practically free of undissolved naphtha. The temperature of the column was adjusted to approximately 85 C.

In the runs. the unsaponifiable matter concentrated in the raffinate phase or naphtha phase is drawn off through the line 48 at the top of the column. It could be appropriately stripped of solvent by steam distillation in the still 49. Subsequently it could be fractionated to distill off fatty acids in the still 56.

The extract phase could be drawn off at 35. similarly steam stripped in still 36 and subjected to fractional distillation in the still 4 l. In run I, there was obtained from the extract phase approximately 1.69% of an oily type of unsaponifiable matter.

There was obtained from the raffinate phase in the run approximately 7.10% of unsaponifiable matter which was of crystalline nature and which was highly enriched in sterols that could readily be recovered in a more purified form by conventional crystallization techniques or by appropriate chemical procedures which do not constitute features of the present invention.

The results and also the operating conditions involved in the several runs are tabulated as follows:

Run l Run2 Runa Feeds:

ids 1 in c. c. per minute 15 l5 15 Ac -goyate e. c. per minute-. 120 120 120 Reflux Naphtha-tate, c. c. per minute. 90 40 Solvlent Ratios: 8 s 8 Na hthi:IIIIIIIIIILI.- 4 e 2. er Coluxnxll, Temp., 85 85 85. 5 Extract Yields Based on Crude Stock:

Per Cent drude Extract 55.1 43.1 c4. 3 Per Cent Distilled Extract 42. 5 31.4 52. 4 Per Cent Pot Residue 12. 11. 7 11.9 Ramnate Yields, Based on Crude Stoc Per Cent Crude Raillnate 44.9 56. 9 35. 7 Per Cent Distilled Railinate- 33. 6 46. 0 24. 2 Per Cent got 1I)iieriil1u%... 11.3 10. 9 11. 5

Based n s a e Yielgsale. Distilled Extract ield 57.9 44.0 66. Calo. Distllledglzxilltate Yield 42. l 56. 0 33. Pro ordtiine'girllilrgm-; 204.0 215. e 194. Acid Value 186. 1 181. 4 189. Per Cent Distillable Acids 77. 2 73. 0 8l. Pro rties, Crude te:

gdine Value 77. 7 99. 7 77. Acid Value 165. 2 176. 9 158. Per Cent Distillable Acids 75. 0 8l. 0 68. Pro rties, Distilled Extract: 227 0 242 2 208 3D maval '20410 20410 20a 71. 2 97. 8 68. 203. 0 202. Gardner Color 4 Evelyn Cglori.. 318 328 3l Iodlerdh ma.' maa 115.9 11e. Distilled Products 155. 8 144. 8 140.

Percentages in the table are by weight. Calculated yields are based on iodine value.

Example II In this example, the raw material comprised crude fatty acid mixtures from soap stocks obtained in the refining of cottonseed oil with small amounts of sodium hydroxide. The raw material was a fatty acid product which is available as a commercial material upon the market. The material was understood to have been prepared by treating the crude soap stock with alkali for several hours to break the residual glycerides and subsequently acidifying the resultant mixture of soaps and unsaponiflable matter.

The mixture of fatty acids and unsaponiable matter was then heated to 90 C. and agitated with sulfuric acid for a period of 16 hours in order to assure the removal of any natural emulsification agents that might be present. In this operation, 300 pounds of sulfuric acid solution per 1000 pounds of crude acids was sufficient.

The sulfuric acid and any other water-soluble constituents were appropriately washed out with water from the treated acids to provide a feed stock for the column 3l. The properties of this stock were as follows:

Iodine value 109.9 Acid value 169.2 Saponication value 184.0 Percent by weight of unsaponiilables 6.87 Color Black Distillable acids '15% by weight In this run, the column was essentially the same as that described in Example I. The feed of fatty acids was made up with naphtha to a concentration of 47.5% by volume in order to assure absence of acids in solid state. In the extraction operation, furfural saturated with water was employed as a polar solvent.' The proportion was 8.4 parte by volume per part of feed stock. Naphtha feed to the lower portion of the column was Iodine Value S read:

. Properties, Crude Extract:

in a proportion of 4.3 to 7.4 parts by volume per par-t of feed stock. The column was operated at a temperature of to 120 F. -The operational data and the results for the several runs in 'this example are tabulated as follows:

Run i Run2 SSS dine Valu Per Cent Dlstillable.- Pro rties, Crude Railnate:

odine Va ue Acid Value Properties, Distilled Extract:

dine Value cid Val Evelyn Color Crude Pr ucts..... Distilled Products...

Percentages are by weight.

The pot residues in the rafnate fractions as obtained in the several runs were very rich in sterols which could readily be recovered by conventional techniques.

'I'he distilled extract acids from the extraction of cottonseed oil foots acids can be further treated to'remove saturated acids of short chain length, e'. g. palmitic acid, and thus to provide a fatty acid of high iodine value. e. g. or thereabouts. Either the original distilled extract or one from which the palmitic acid is removed is especially suitable in the manufacture of alkyd resins. The percent of palmitic acid may. for example, be reduced by fractionally distilling the extract acids, or by dissolving the extract acids in a solvent such as methanol and crystallizing of! the palmitic acid.

'I'he residues from the extract portion were comparatively poor in unsaponiflable matter and the unsaponiilable matter recoverable was of an oily non-sterol nature. The unsap'oniflable mat'- ter of the extract of run 1 comprised 1.1% while the ralnate contained 9.55% (percentages by weight) It would appear that the ratllnate fraction may contain small amounts of unsaponifled glycerides. If desired, these could be split after the extraction operation but before distillation in order to obtain a larger yield of distilled acids. Such distillation, however, is not essential. The

vdistillation residues constitute excellent sources for the further purication of sterols.

- Example III In this example, soap stocks from the refining of soybean oil was employed as a starting ma.- terial. 'I'he saponiflcation ofresidual glycerides or oil in this stock was conventional. The soaps were then acidified with sulfuric acid and the fatty acid layer was separated. It wat found desirable further to treat the fatty acids with 15% sulfuric acid as in Example I in order to eliminate emulsifying agents.

If desired. the acidifled stock or soap mixtures- Iodine value 136.9 132.5 Acid value 178 177.1 Distillable acids 82.7 81.5

' operated at temperatures approximately 85 F.

The stock was introduced into the column as a 50% solution in naphtha. 'The operational data and the results obtained in the several runs are tabulated as follows:

Run Run 2 Runii Runi Run 5 Rune Feeds:

Feed Solution Rate, 50% naphtha 120 60 45 45 45 60 Furiural, Rate 40 20 l5 15 l5 15 Reflux Naphtha,

Rate 38 12 13 8 8 10 Type of Furi'ural.. Wet Dry Wet Dry Wet Wet Solvent Ratios:

Furiural 6-1 6-1 6-1 6-1 6-1 8-1 Naphtha 3-1 2. 2-1 2. 7- 1 2. l-l 2. l-l 2. 3-1 Column Temperature,

85 85.5 85 85.5 85.5 85 Extract Yields Based on Crude Stock:

Per Cent Crude Extract 40.9 34 54.4 51.3 71.2 82.5 Per Cent Distilled Extract 35. 27. 6 47.3 44. 7 64. 2 74. 3 Per Cent Pot Residlle 5. 9 6. 4 7. 1 6. 6 7.0 8. 2 Raifinate Yields,

Based on Crude Stock:

Per Cent Crude Ranate 59. 1 66 45. 6 48. 7 28.8 17. 5 Per Cent Distilled a n e 47. 2 53. 4 31. 2 34. 7 15. 4 6. 45 Per Cent Pot Residue 11.9 12.6 14.4 14.0 13. 4 11.05 Yields Based on Distillable Acids:

Distilled Extract Yield 42. 7 34. l 60. 5 56. 3 80. 7 92. 1 Distilled Ralnate Yield 57. 3 65. 9 39. 5 43. 7 19. 3 7. 9 Properties, Crude Extract:

Iodine Value 173. 7 172. 6 166. 2 165. 5 156. 1 147. 6 Acid Value 184. 8 176. 4 189. 8 192. 3 192. 5 Per Cent Distillable Acids 85. 78. 7 87.0 87.0 00.1 90. 0 Properties, Crude Rafiinate:

Iodine Value 103.6 114.0 94. 4 99. 4 79. 2 90. 2 Acid Value 167 177. 2 150. 8 159. 4 137. 3 77. 3 Distillablc Acids... 79.0 81.8 67.0 71. 2 52.8 36.8 Properties, Distilled Extract:

Iodine Value 180. 2 180. 1 170. 5 169. 4 161. 3 151. 3 Acid Value 202 201. 2 201. 6 202.4 202. 3 202. 4 Gardner C0lor. 6 7-8 9-10 l0 7-8 6-7 Evelyn Color 276 142 167 113 232 275 Properties, Distilled Rafllnate:

Iodine Value 99. 3 109.8 91.0 96. 2 66.8 59. 7 Acid Value 202. 9 202. 5 204 0 204.6 204.8 183. 1 Gardner Color Lif-5 3-4 6-8 6 8-9 17 Evelyn Color 207 295 183 221 133 6 IodineValue S read:

Crude Pro uctS... 70.1 58.6 71.8 66.1 76.9 57.0 Distilled Products. 80. 9 70. 3 79. 5 73. 2 92. 5 91.6

i Ralnate Yields Based on Cru The unsaponiilable matter was concentrated in the railinate which was found to contain 5% of crystalline unsaponiilable' matter in run v1 while the extract from run 1 was found to contai'n 1.92% of reddish oily liquid. Run 6 yielded a raffinate which contained 11.75% of crystaly line unsaponifiable matter while the extract contained 1.46% oily liquid unsaponifiable matter. The unsaponiflable matter of the raffinate could readily be separated out into sterol fractions in accordance with well known techniques for-the purification of sterols.

Example IV As previously stated, the invention is particularly well adapted for the preparation of concentrates of sterols from conventional soap stocks as obtained in the refining of glycerlde oils. However, it is found that similar techniques are also applicable to the preparation of concentrates of sterols of tall oil from a mixture of the fatty acids and unsaponifiable matter as well as other constituents of tall oil.

In a specific example, a stock was obtained by selective esteriflcation of fatty acids of tall oil and neutralization of the rosin acids and separation of the methyl esters and unsaponifiable matter from the rosln acid soaps in a countercurrent naphtha extraction of the soap solution in accordance with the process described in an application Serial No. 47,836. esters and unsaponifiable matter was subjected to a conventional splitting operation by treating it with alkali, then-with sulfuric acid to liberate the fatty acids. The mixture was then washed with water until water-soluble constituents were substantially eliminated. 'I'he characteristics of the resultant stock were: 1

Iodine value 142.7 Acid value 160.1 Unsaponiflables 14.2%

The mixture comprising essentially free fatty acids and unsaponiable matter including sterols. of which sitosterol constituted a large proportion, was subjected to fractionatlng in a column 3|. The dimensions of the column were: diameter, 2 inches; height from the polar solvent feed to the inlet for stock, 43 ft.; height from the inlet of stock to the inlet for naphtha, 36 feet. The several runs were made with furfural saturated with water, in a proportion of 8 parts by volume per part by volume of stock. The naphtha ratio was varied from 1.3 to 2.6 parts by volume. The critical data for the several runs of this example are tabulated as follows:

Run l Run 3 Feeds:

Feed Solution Rate 47% naphtha by volume Furiural feedRate, cc./min Reflux Naphtha Feed Rate, cc./lnin.. Solvent Ratio:

Furfural Naphtha (Parainic). Column Temperature. Extract Yield Based on Crude Stock: Per Cent Crude Extract Per Cent Distilled Extract. Per Cent Pot Residue d Sto Per Cent Crude Railinate. Per Cent Distilled Raiilnate.. Per Cent Pot Residue Yields Based on Distillable Acids:

Distilled Extract Yield Distilled Railinate Yield Properties, Crude Extract:

Iodine Value Acid Value Per Cent Distillable Acids Per Cent Unsaponiilable Matt The mixture of' |Run1 Run Run3 Pro rtles, Cnide Rafilnate: I

eodine Value l 11324 Acid Value 126. i Per Cent Dlstillable Acids 55. 3 Per Cent Unsaponiilahle Matter 38. 6 Pro ierties, Distilled Extract:

Y odlnc Valuel 145. 164. 7 169. 8 Acid Value 191. 2 187. 2 188. 3 Gardner Color... 9 9-1'0 9 Evclvn Color 213 1.8 1X5 Per ent Unsaponiable Matter 4.67 6.96 6. PeriCeniRilslixARci.. .t l. 85 2. 59 2. 7l

Pro t as, st e a na .ez

leidine Value 106. l 92. 0 Acid Value 191. 4 189. 5 Gardner Color E vel Color 326 60 Per .ent Unsaponiiiable Matter 4. 52 5.61 Iodine Value S read:

Crude Pro ucts 52.6 5.1.2 Distilled Products 58. 71,8

In the data, percentages are by weight.

As a result of the several runs, a raiilnate fraction rich in unsaponiflable matter, o f. which sterols were a main constituent, was taken off at the top of the column. A liquidAunsaponiflable matter of pine-like odor was taken on in the extract phase.

. I claim:

l. In a process of obtaining a concentrate of sterols, the steps of acidifying a soap from a glyceride oil containing sterols to liberate free fatty acids, washing the resultant mixture comprisingfatty acids of different degrees of saturation and unsaponiiiable matter of a glyceride oil with water to remove water soluble constituents, then intimately commingling said mixture with a system of a polar solvent and a non-polar solvent, which is not completely miscible with the polar solvent, separating the system into two phases, one of which comprises a liquid extract phase of polar solvent in which are dissolved fatty acids of a relatively high degree of unsaturation and a low sterol content, and the other of which comprises a liquid raffinate phase of non-polar sclvent in which is dissolved a fraction of relatively more saturated fatty acids enriched in sterols, separating the phases, evaporating the solvents from the raffinate phase, and selectively removing fatty acids therefrom to provide said concentrate.

2. In a method of obtaining a. fraction rich in sterols from a mixture comprising higher fatty acids of different degrees of unsaturation, oily unsaponiable matter and sterols, the steps of intimately commingling the mixture with a system comprising a polar solvent and a, non-polar solvent which is not completely miscible with the polar solvent to form (A) a liquid extract phase of polar solvent in which is dissolved a fraction of relatively unsaturated fatty acids impoverished in sterols and rich in oily unsaponiiiable matter, and (B) a liquid ramnate phase of nonpolar solvent in which is dissolved a fraction of relatively saturated fatty acids enriched in sterols, separating the phases, evaporating the nonpolar solvent from the ramnate phase and selectively removing the fatty acids from the mixture of fatty acids rich in sterols to provide said concentrate.

3. In a process of obtaining sterols from foots rich therein resulting from the refining of glyceride oil with minor amounts of alkali to neutralize `fatty acids and eliminate break and subsequently separating relatively small amounts of a'mixture of soaps of fatty acids, glyceride oil and unsaponiable material including an enrichment of sterols as the foots, the steps of splitting residual glycerides and acidifying the soaps in the foots, washing out with Water the water soluble constituents in the resultant mixture of free fatty acids and unsaponiiiable constituents, then intimately commingling the resultant mixture of free fatty acids and unsaponifiable constituents with a partially miscible system of a liquid polar solvent and a liquid non-polar solvent. whereby to obtain two liquid phases, one constituting an extract phase of relatively highly unsaturated fatty acids and oily unsaponifiable matter and the other comprising a raiiinate phase of relatively saturated fatty acids and unsaponiiiable matter rich in sterols, separating the phases and removing the solvent media from the ramnate phase to obtain said concentrate.

4. In a process of obtaining a concentrate of sterols from foots acids rich in sterols, the Steps of intimately contacting said acids with a mixture of polar solvent and non-polar solvent, the components of the mixture being incompletely soluble in each other. separating an extract phase of polar solvent enriched in unsaturated fatty acids and oily unsaponiable matter and a raffinate phase containing relatively saturated fatty acids enriched in sterols, and evaporating the non-polar solvent from the latter phase to obtain said concentrate.

5. In a process of obtaining a concentrate of sterols from acids from glyceride oils containing sterols obtained by rening the oil with .05 to 3% by weight of caustic soda, separating the resultant foots from the oils, the steps of splitting the free glycerides, acidifying the soaps of fatty acids, washing out the salts from the resultant mixture, intimately contacting the mixture of free fatty acids and unsa-poniflable matter with a commingled system of a polar solvent and a non-polar solvent no more than partially miscible with the polar solvent, whereby to obtain two liquid phases one of which is an extract solution of polar solvent rich in unsaturated fatty acids and poor in sterols and the other of which is a railinate solution of non-polar solvent rich in saturated fatty acids and sterols, separating the phases and recovering the raihnate from the non-polar solvent.

6. In a process of obtaining a concentrate of sterols, the steps of treating foots from the reflning of glyceride oils with alkali with additional alkali to saponify glycerides residual in the foots, then acidifying the soaps obtained, washing out water soluble salts yformed by the acidification, then contacting the solution of fatty acids and unsaponiable matter with a polar solvent and naphtha whereby to obtain two phases. one comprising polar solvent containing in solution a concentration of fatty acids and the other comprising naphtha containing in solution a concentration of unsaponiable matter including sterols, separating the phases and recovering from the naphtha phase said concentrate of unsaponiable matter.

7. In a process of obtaining a fraction rich in sterols from a mixture comprising higher fatty acids of varying degrees of unsaturation, oily unsaponiable rmatter and sterols, the steps of intimately commingling 1 part by volume of the mixture with an incompletely miscible system comprising 2 to 30 volumes of a polar solvent and .2 to 10 volumes of naphtha, in mutual countercurrent iiow with respect to each other, the temperature of the system being within a range of 60 to 200 F., allowing the system to separate 17 into phases. one comprising polar solvent containing in solution an enrichment of fatty acids and the other comprising naphtha containing in solution an enrichment of sterols and separating the sterols from the naphtha.

8. The steps as defined in claim 7 in which the polar solvent is furfural.

9. The steps as defined in claim 7 in which the polar solvent is furfural containing water in solution.

10. The steps as defined in claim l in which the fatty acids in said concentrate are further subjected to saponication and the sterols are extracted out with naphtha.

11. The steps as defined in claim 1 in which the fatty acids of said concentrate are saponied with alkali, the soaps are made up into solution in water and a water soluble alcohol and the sterols are extracted out with naphtha.

12. The steps as defined in claim 1 in which the concentrate is further subjected to distillation under vacuum to remove fatty acids and to provide a pitch residue further enriched in sterols. the residual fatty acids in said pitch then being saponifled. the saponied mixture being made up into solution in water and a lower alcohol and the unsaponifiable matter being extracted out with a solvent.

13. In a process of obtaining a concentrateof sterols from a mixture of relatively highly unsaturated fatty acids and relatively saturated fatty acids containing said sterols, the steps of intimately contacting said mixture with a system of commingled but mutually incompletely miscible polar solvent and non-polar solvent, to form an extract phase of polar solvent in which is dissolved a concentrate of relatively unsaturated fatty acids and oily unsaponiiiable matter and a rafllnate phase of non-polar solvent in which is dissolved a concentrate of sterols and relatively saturated fatty acids, and separating the phases from each other.

14. In a process of obtaining a concentrate of sterols from glycerides of fatty acids of different degrees of unsaturation containing said sterols in relatively small amount, the steps of treating the glycerides with alkali in an amount partially to form a sludge comprising a small amount of soaps having a high sterol content. separating off the resulting sludge, liberating the free fatty acids from the soaps, intimately contacting the resultant mixture of free fatty acids ana sterols with a system of mutually incompletely miscibie but commingled polar and non-polar solvent, separating the system into two phases, one comprising a liquid solution of polar solvent in which are selectively dissolved fatty acids of relatively high degree of unsaturation and low sterol content and the other of which comprises a liquid raflinate phase of non-polar solvent in which is dissolved a fraction of relatively more saturated fatty acids enriched in sterols, separating the phases and selectively removing fatty acids from the sterols to provide said concentrate.

15. A process as defined in claim 14 in which the glyceride oil is treated with .1 to 3 by weight of alkali.

16. A process as defined in claim 14 in which the glyceride oil is treated with .1 to 3% of sodium hydroxide.

17. In a process of obtaining a concentrate of sterols from glycerides of fatty acids of different degrees of unsaturation, said glycerides containing sterols, the steps of treating the glycerides with 0.1 to 3% by weight of sodium hydroxide to form a sludge comprising a small amount of soaps of the glyceride fatty acids which sludge also contains a high sterol content, separating off the resultant sludge of soaps, acidifying the soaps with acid to liberate free fatty acids, washing out the resultant sodium salts from the acidified mixture with water, intimately contacting the washed mixture with a system of commingled furfural and naphtha, separating a furfural phase containing in solution a concentration of relatively highly unsaturated fatty acids impoverished in sterols and a naphtha phase containing a concentration of fatty acids of relatively low degree of unsaturation and being enriched in sterols, and separating fatty acids from the sterols to obtain said concentrate of sterols.

ROGER M. CHRISTENSON.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,362,605 Yoder Nov. 14, 1944 2,499,430 Vogel et al. Mar. 7, 1950 2,499,877 Porter Mar. '1, 1950 

1. IN A PROCESS OF OBTAINING A CONCENTRATE OF STEROLS, THE STEPS OF ACIDIFYING A SOAP FROM A GLYCERIDE OIL CONTAINING STEROLS OF LIBERATE FREE FATTY ACIDS, WASHING THE RESULTANT MIXTURE COMPRISING FATTY ACIDS OF DIFFERENT DEGREES OF SATURATION AND UNSAPONIFIABLE MATTER OF GLYCERIDE OIL WITH WATER TO REMOVE WATER SOLUBLE CONSTITUENTS, THEN INTIMATELY COMMINGLING SAID MIXTURE WITH A SYSTEM OF A POLAR SOLVENT AND A NON-POLAR SOLVENT, WHICH IS NOT COMPLETELY MISCIBLE WITH THE POLAR SOLVENT, SEPARATING THE SYSTEM INTO TWO PHASES, ONE OF WHICH COMPRISES A LIQUID EXTRACT PHASE OF POLAR SOLVENT IN WHICH ARE DISSOLVED FATTY ACIDS OF A RELATIVELY HIGH DEGREE OF UNSATURATION AND A LOW STEROL CONTENT, AND THE OTHER OF WHICH COMPRISES A LIQUID RAFFINATE PHASE OF NON-POLAR SOLVENT IN WHICH IS DISSOLVED A FRACTION OF RELATIVELY MORE SATURATED FATTY ACIDS ENRICHED IN STEROLS, SEPARATING THE PHASES, EVAPORATING THE SOLVENTS FROM THE RAFFINATE PHASE, AND SELECTIVELY REMOVING FATTY ACIDS THEREFROM TO PROVIDE SAID CONCENTRATE. 